Incandescent lamp.



Witnesses G. P. STEINMETZ.

INGANDESCBNT LAMP.

APPLICATION FILED SEPT. 13, 1908.

Patentd May 20, 1913.

I UNITED STATES PATENT-OFFICE. v

CHARLES r. s rnmmn'rz, or SGHENECTADY, NEW YORK, AssIGNon TO GEKEBALELECTRIC COMPANY, A coaronarxon or NEW YORK.

mcnnnnscnn'r LAMP.

Specification of Letters Patent.

Applicationfiled September 8, 1903. Serial No. 452,057.-

ma ed s 20, -1913-.

. phenomena are in the nature of electrical bulb.

discharges taking place across the leadingin wires or parts of lampfilaments across which adifierence of potential exists. The discharge insome cases is invisible and may harm the filament only very slowly, orit may be visible, continuing visible for a short time and then ceasing.In the latter case, of course, the filament is damagedmore rapidly. Thedischarge seems more likely to take place when the vacuum in the lamphas deteriorated, because of the liberar tion of gases occluded by thefilament or condensed upon the inside walls of the lamp According to myinvention I dispose .a wire strip or globule of met-allicmagnesium,calcium or lithium, or, alloys containing these metals, near theleading-in wires of thelamp in a manner hereinafter described,

, so that the electrical discharge takes place across these wires orstrips in preference to taking place between adjacent. parts of thefilament, or filaments. The discharge seems to have the efiect ofvaporizing a small amount of these metals. I find that thisapparentlyhas the effect of completely absorbing or abstracting thegases which may have accumulated in the globe, and in this way the highvacuum is automatically restored and maintained. My invention isillustrated in the accompanying drawings,a'nd will be more clearlyunderstood by reference to the following description taken in connectiontherewith Figure 1- shows an incandescent lamp in which the filament isarranged in several loops, and illustrates one way of attaching themagnesium or calcium w res; Figs. 2, 3

; illustrate diagrammatically alternative ways of attaching thevaporizable metals; Fig. 4 is an enlarged view showing how the mag- Iprepared to state.

enough to carry away nesium wires may be attached without welds mg.

In Fig. 1 a lamp is shown of the type now commonly used 1n connectionwith metallic filaments. The filament loops 1, are supported by wires 2attached to the standard 3,

and are arranged in the usual manner within'the glass bulb 4. Currentis'supplied to the filaments l by.intermediate leading-in w1res.5, whichmay be copper, nickel or platinum, but which in either case are at'tached to a short piece of platinum wire 6,

passing through the glass stem 7. Wires 8 consisting of oneof the metalsmentioned,

say magnesium, are attached to the leadingin wires 5, as by welding orattaching them as is lllustrated in Fig. 4: to whichre erence will againbe made.' The magnesium wires 8 are so arranged as to approach oneamother more closely than do the leading-in wires or the adjacent legs ofthe filament to which the leading-in wires are attached, so that thedischarge will take place across the space between the magnesium wires 6and not at other points. As above explained, a

small amount of metallic magnesium will be vaporized by the discharge,and this a parently has the effect of absorbing t e liberated gases andproducing a practically perfect vacuum. As to the exact cause to whichthis effect is due, I

am not at present In Fig. 2 thevmagnesium or calcium wires arerepresented as applied-to a single loop of filament; but, of course,they may be applied in the same way with a multi-loop lamp. In thisfigure the leading-in wires 6,

magnesium wires 9 and the'filament 1 are all in series,'th e magnesiumwires, 9 serving to carry current from the platinum leadingin wires 6 tothe filament 1. The magnesiu'mwires are here shown as being welded tothe filament 1 at one end and to the leading-in wires 6- at the otherend. The wires 9 are bent toward each other as is clearly.

shown so that the electricaldischarge will be sure to take place betweenthe magnesium wires instead of between the opposite legs of the filamentor between the leading-in wires. The wires v9 must be made heavy theheat conducted thereto by the incandescent filament with sufficientrapidity to prevent their melting.

Fig. 3 is a view showing the filament 1 attached to intermediateleading-in wires which are bent toward each other and are connected inturn to the platinum leading-in wires 6 in the usual manner. A smalllobule of lithium 1-0 is attached to the lea ingin wires 5 at pointswhere the distance between these wires is least. -The lithium willadhere readily to these wires because of its small bulk' and when theelectrical discharge takes place it will vaporize a small amount of thelithium which, as has been stated, will absorb gases.

Fig. 4 is an enlarged fragmental view of the stem of the lamp. Theintermediate leading-in wires 5 are shown, each connected at one end bya weld to the platinum wire 6 assing through the glass stem 7 in Fig. 1.--h,e filament loops 1 are not shown in this figure but of course are tobe understood as attached .to the other ends of the wires 5. Magnesiumribbons 11 are attached to the wires 5 by piercing a hole through theribbons at either end, slipping the wires 5 through these holes, andthen. pinching the ends of the ribbons 11 around the leading-in wires 5as is clearly shown in the figure, the magnesium ribbons being bowedtoward each other, so that if an electrical discharge takes place itwill be sure to take place bevelop, a filament disposed therein, and aconductor containing metal whose vapors havegreat afiinity for gasesconnected with Wires supplying current to said filaments and conductorsconsisting of metals having great afiinity for gases when vaporizedelec-, trically connected 1 to said leading-in wires the distance atsome point between said condoctors being lessv than that between theleading-in wires, said conductors forming at said point terminals for.the easiest path for electrical discharges across the filament circuitand being adapted to vaporize by such discharges upon a deterioration ofthe vacuum in-the envelop during operation of the lamp.

4. The combination in an incandescent lamp of an evacuated envelop,filaments disposed therein, means for supplying said filaments withcurrent, and means made operative by a deterioration of the vacuum insaid envelop during the life of the lamp for producing therein a metalvapor having a great aflinity forxgases and thereby automatically actingto restore the vacuum. during operation of the lamp.

5. The combination in an incandescent lamp of an evacuated envelop,filaments disposed therein, means for supplying said-filaments withcurrent, and means made operative by the electrical discharge occurringupon a deterioration of the-vacuum in said envelop for producing thereina metal vapor having a great aflinity for gases and therebyautomatically acting to restore the vacuum during operation of the lamp.

In witness whereof, I have hereunto set my hand this 5th day ofSeptember, 1908.

CHARLES P, STEINMETZ.

Witnesses:

BENJAMIN B. HULL, MARGARET-A. DELEHANTE.

